bioremediation of oil contaminated soils by washing under static conditions

In this research five different solutions were used to wash an oil contaminated soil with the initial tph (total petroleum hydrocarbon) content of 46 g kg^-1 (grams of tph per kg of dry soil). the solutions were a basal mineral medium (solution i), the basal mineral medium inoculated with petroleum degrading microorganisms (solution ii), the basal mineral medium inoculated with a culture of petroleum degrading microorganisms and supplemented with a commercial washing powder (solution iii), the basal mineral medium inoculated with the microorganisms and supplemented with tween 80 (solution iv), and the basal mineral medium inoculated with the microorganisms and supplemented with sucrose (solution v). washing was performed by saturation of the soil with the solutions in columns and intermittent mixing. solutions iv and v performed better than the others, giving more than 90% tph removal in two months. in a separate experiment tph removal was monitored as a function of time during washing. solution v reduced the tph content of the soil more rapidly than the others, with more than 70% tph removal in 28 days. addition of sand particles to the soil for the purpose of better mixing resulted in marginal positive effects.